1. Field of the Invention
The present invention relates to a method and a device for measuring the angle of the slant surface of an optical component.
2. Description of the Related Art
In an optical device having slant connecting end surfaces, it is required to accurately connect and adjust the connecting end surfaces so as to prevent rotational angle dephasing of the slant end surfaces or misaligned optical axes.
Generally speaking, fibers are joined together by welding or connectors. The fiber has a limited numerical aperture so that a laser beam has a fixed range of diffusion angle after it comes out of the fiber. To avoid the diffusion of the laser beam, a fiber collimator plays an important role in the fiber optic transmission. The fiber collimator can guide the laser beams into the fiber and convert the laser beams to parallel laser beams through a GRIN Lens (Graded INdex lens).
To decrease reflection of the laser beams in the fiber, the U.S. Pat. No. 5,809,193 uses a number of ferrules joined together, wherein the ferrules have a slant surface. According to the law of reflection, when the laser beams are in the interface of the slant surfaces of two ferrules, the amount of reflecting back along the original irradiation routes of the laser beams is decreased. The ferrule of the fiber thread in the fiber collimator also has an end surface with a slant surface. A fiber collimator, as illustrated in FIG. 1, comprises a GRIN Lens in conjunction with a ferrule assembly comprising an optical fiber. A fiber collimator can enormously decrease the amount of reflection of the laser beams. In the process of fiber assembly, the ferrule is formed with a certain inclined angle by grinding. The accuracy of the inclined angle of the slant surface of the ferrule influences the exit angle of the laser beams of the fiber collimator. In order to maintain the exit angle of the laser beams of the fiber collimator within a fixed range of tolerance, the angle of the slant surface of the ferrule must be maintained within a fixed tolerance. Thus, it is important to obtain the angle of the slant surface of the ferrule by using an accurate measuring method while manufacturing the fiber collimator.
An object of the present invention is to provide a device and a method to measure the angle of the slant surface of the ferrule or other optical components.
In the invention, the slant surface of the ferrule faces exactly toward the slant surface of the GRIN Lens, and the ferrule is spaced from the standard component by a pre-defined distance. Then, laser beams are input into the vertical surface of the standard component such that two oval projections are created on a screen by reflection of the slant surface of the standard component and the slant surface of the ferrule, respectively. As a result, the angle of the slant surface of the ferrule is obtained on the basis of the specification of the standard component and the dimensions of the two oval projections.
A detailed description will be given by the following embodiments with reference to the accompanied drawings.